Research funded by the Bill & Melinda Gates Foundation supports a three-pronged approach in teacher evaluations that includes students' test scores, classroom observations conducted by multiple people and feedback from students. Check out this story from The Washington Post: http://www.washingtonpost.com/national/gates-study-weve-figured-out-what-makes-a-good-teacher/2013/01/08/05ca7d60-59b0-11e2-9fa9-5fbdc9530eb9_story.html.